The present invention pertains to the field of cooling systems, and in particular, to a microprocessor control system that provides single stage thermostat control for a two-stage cooling system.
Many air conditioner controls include a two-stage thermostat for providing dual stage cooling, wherein the first stage of the thermostat operates the unit on low cooling and the second stage of the thermostat operates the unit on high cooling. For example, a typical two-stage thermostat includes two small mercury bulb contacts on a bi-metal sensor that close and open as a function of the movement of the bi-metal sensor in response to changing room temperatures. If the present room temperature is above a desired temperature set point, for example, one degree to two degrees above the set point, then the first mercury bulb contact closes to provide low stage cooling. If the room temperature continues to rise to, for example, three degrees above the desired temperature set point, then the second mercury bulb contact closes to provide a high stage cooling. When the cooling load is satisfied, both of the mercury bulb contacts in the thermostat sequentially open or deactivate, thereby terminating the cooling cycle. Thereafter, when the thermostat contacts close indicating a new cooling load to be satisfied, the air conditioning control repeats the same identical cooling cycle.
Disadvantages of this type of air conditioning control include the requirement for a two-stage thermostat for providing dual rates of cooling and the existence of large swings in room temperature.
Briefly stated, when a single-stage thermostat is appropriately connected to a two-stage cooling system, a microprocessor control activates low and high stages of cooling based on preset parameters. The cooling load requirement is determined and compared to the maximum load requirement that can be satisfied in low-stage cooling mode and the minimum load requirement which can be satisfied in high-stage cooling mode. The desired low-stage cooling time limit is then determined for the next cycle. After the first cycle, the desired low-stage cooling time limit may be equal to zero in which case the next cycle is spent in high-stage cooling mode, or, if greater than zero, the next cycle runs in low-stage cooling mode up to the desired low-stage cooling time limit, with an additional high-stage cooling mode run if the thermostat is not satisfied within the desired time.
According to an embodiment of the invention, a method for selectively providing a low cooling mode and a high cooling mode of a cooling cycle in an air conditioning unit as a function of a previous cooling cycle includes storing a previous duration of operation of a low cooling mode and a previous duration of operation of a high cooling mode of a previous cooling cycle; determining an existence of a cooling load to be satisfied; recalling the stored duration of the previous low cooling mode; providing a low cooling mode for a selected first time period dependent upon the stored duration of the previous low cooling mode; and terminating the low cooling mode if the cooling load is satisfied during the selected first time period.
According to an embodiment of the invention, a method for selectively providing a low cooling mode and a high cooling mode of a cooling cycle in an air conditioning unit as a function of a previous cooling cycle includes storing the duration of a previous cooling cycle; determining the existence of a cooling load to be satisfied; recalling the stored duration of the previous cooling cycle; providing a low cooling mode for a selected first time period dependent upon the time duration of the previous cooling cycle and the determination of the existing cooling load to be satisfied; and terminating the low cooling mode if the cooling load is satisfied during the selected first time period.
According to an embodiment of the invention, an adaptive control system for providing a low cooling mode and a high cooling mode of a cooling cycle in an air conditioning unit as a function of a previous cooling cycle includes means for storing a previous duration of operation of a low cooling mode and a previous duration of operation of a high cooling mode of a previous cooling cycle; means for determining the existence of a cooling load to be satisfied; means for recalling the stored duration of the previous low cooling mode; means for providing a low cooling mode for a selected first time period dependent upon the stored duration of the previous low cooling mode; and means for terminating the low cooling mode if the cooling load is satisfied during the selected first time period.
According to an embodiment of the invention, an adaptive control system for providing a low cooling mode and a high cooling mode of a cooling cycle in a furnace as a function of a previous cooling cycle includes means for storing the duration of a previous cooling cycle; means for determining the existence of a cooling load to be satisfied; means for recalling the stored duration of the previous cooling cycle; means for providing a low cooling mode for a selected first time period dependent upon the duration of the previous cooling cycle and the determination of the existing cooling load to be satisfied; and means for terminating the low cooling mode if the cooling load is satisfied during the selected first time period.
According to an embodiment of the invention, a method for providing a low cooling mode and a high cooling mode of a cooling cycle in a current cycle of an air conditioner unit as a function of the previous cooling cycle wherein the current cooling cycle is a function exclusively of time run in the low cooling mode and time run in the high cooling mode of the previous cooling cycle includes the steps of (a) determining an existence of a cooling load to be satisfied; (b) running the unit in the low cooling mode for a first time interval that does not exceed a predetermined limit; (c) running the unit in the high cooling mode for a second time interval until the cooling load is satisfied; (d) calculating a cooling load requirement as a function of the first time interval and the second time interval; and (e) predetermining the low cooling mode time limit for a next cycle from the calculated cooling load requirement.